\begin{tikzpicture}
	\pgfmathsetmacro{\r}{2}
	\pgfmathsetmacro{\a}{35}

	\tkzDefPoints{0/0/O, 2/0/A, 0/2/C, -2/0/E}
	\tkzDefPoint(\a:\r){B}
	\tkzDefPoint(90+\a:\r){D}

	\tkzDrawSegments(O,A  O,B  O,C  O,D  O,E)
	\tkzMarkRightAngle(A,O,C)
	\tkzMarkRightAngle[size=0.3](B,O,D)
	\tkzLabelPoints[right](B, C, D)
	\tkzLabelPoints[below](A, O, E)
\end{tikzpicture}

